<?php
namespace woodlsy\pay\alipay\aop;
/**
 *   加密工具类
 *
 * User: jiehua
 * Date: 16/3/30
 * Time: 下午3:25
 */

class AopEncrypt
{
    /**
     * 加密方法
     * @param string $str
     * @return string
     */
    function encrypt($str,$screct_key){
        //AES, 128 模式加密数据 CBC
        $screct_key = base64_decode($screct_key);
        $str = trim($str);
        $str = addPKCS7Padding($str);

        //设置全0的IV
        $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128,MCRYPT_MODE_CBC);
        $iv = str_repeat("\0", $iv_size);

        $encrypt_str = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $screct_key, $str, MCRYPT_MODE_CBC, $iv);
        return base64_encode($encrypt_str);
    }

    /**
     * 解密方法
     * @param string $str
     * @return string
     */
    function decrypt($str,$screct_key){
        //AES, 128 模式加密数据 CBC
        $str = base64_decode($str);
        $screct_key = base64_decode($screct_key);

        //设置全0的IV
        $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128,MCRYPT_MODE_CBC);
        $iv = str_repeat("\0", $iv_size);

        $decrypt_str = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $screct_key, $str, MCRYPT_MODE_CBC, $iv);
        $decrypt_str = stripPKSC7Padding($decrypt_str);
        return $decrypt_str;
    }

    /**
     * 填充算法
     * @param string $source
     * @return string
     */
    function addPKCS7Padding($source){
        $source = trim($source);
        $block = mcrypt_get_block_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);

        $pad = $block - (strlen($source) % $block);
        if ($pad <= $block) {
            $char = chr($pad);
            $source .= str_repeat($char, $pad);
        }
        return $source;
    }
    /**
     * 移去填充算法
     * @param string $source
     * @return string
     */
    function stripPKSC7Padding($source){
        $char = substr($source, -1);
        $num = ord($char);
        if($num==62)return $source;
        $source = substr($source,0,-$num);
        return $source;
    }
}
